Wireless communications have been evolving toward ever increasing data rates (e.g., from IEEE 802.11a/g to IEEE 802.11n to IEEE 802.11ac). In high-density deployment situations, overall system efficiency may be come more important than higher data rates. For example, in high-density hotspot and cellular offloading scenarios, many devices competing for the wireless medium may have low to moderate data rate requirements (with respect to the very high data rates of IEEE 802.11ac). A recently-formed study group for Wi-Fi evolution referred to as the IEEE 802.11 High Efficiency WLAN (HEW) study group (SG) (i.e., IEEE 802.11ax) is addressing these high-density deployment scenarios.